The present invention relates to a controller for operating a louvered blind. More particularly, the present invention relates to an improved cord lock for a louvered blind controller system that encloses an operating cord or chain within a control handle.
Louvered blinds shield window and door openings to block the passage of light and to provide privacy. Louvered blinds are constructed from a plurality of louvers or vanes that can be individually rotated about an axis to open and to close the blind. Typically, the rotation of such vanes is controlled by rotation of a wand attached to a gear mechanism or by pulling on a chain engaged with a gear mechanism.
In a blind where the vanes hang vertically, the blind can be opened and closed by moving the vanes to one side of the opening. This operation is controlled by pulling a cord attached to a mechanism, or by physically pulling the vanes along a track attached to the head rail of the window blind. In a window blind where the vanes are horizontally oriented, the window blind can be raised and lowered by pulling a cord attached to a mechanism that engages the cord to lock the location of the vanes at a desired elevation.
Conventional blinds incorporate a looped cord having two cord lengths. The cord lengths are attached to a mechanism inside the blind that moves the vanes, and either cord length can be pulled to selectively open or close the blind vanes. In other blind designs, either cord length can be pulled to selectively open or close the blind across the opening.
Such looped cords hang free from one side of the blind, and the necessary length of the looped cord depends on the width of the opening. Blinds for large openings require a looped cord extending to the floor, which creates a potential safety hazard for small children. Because of this hazard, efforts have been made to eliminate looped cords from blinds.
In one design of a blind having vertical vanes, a wand controls the rotation of the vanes, and the vanes are manually pulled across the opening to close the blind. Although such blind does not incorporate a looped cord, the blind requires a person to walk along the length of the opening to open or close the blind. This procedure can be difficult when furniture or other obstructions block the window or door opening.
Another concept in window blinds eliminates the looped cord by incorporating an electric powered drive mechanism which selectively operates the blind and the individual vanes. The electric mechanism substantially increases the cost of the window blind and increases the number of mechanical components subject to failure.
One window blind concept is shown in U.S. Pat. No. 5,472,035 to Biba et al. (1995), wherein an elongated wand incorporated a lengthwise passage having an open slot along one side of the wand to permit vertical movement of components relative to the wand. However, the slot substantially weakens the wand and requires additional material for strength. In another design, U.S. Pat. No. 5,465,775 to Biba et al. (1995) disclosed an endless cord operating loop having lift cords connected to the endless loop. Although these concepts position a cord within an elongated wand, such concepts require numerous operating parts and are expensive to manufacture.
Accordingly, a need exists for a improved vertical blind system and cord lock that encloses a cord for operating the blind. The system should be easy to manufacture and to operate.